Effects of drainage ditches behind dams of plain reservoirs on soil water and salt transport in downstream farmland in arid regions
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DOI:10.7606/j.issn.1000-7601.2020.02.06
Key Words: plain reservoirs  downstream farmland  soil water and salt transport  drainage ditches  HYDRUS simulation  arid areas
Author NameAffiliation
HUANG feng School of Water Conservancy and Civil Engineering, Xinjiang Agricultural University, Urumqi, Xinjiang 830052, China 
YAN Xinjun School of Water Conservancy and Civil Engineering, Xinjiang Agricultural University, Urumqi, Xinjiang 830052, China 
MAO Haitao School of Water Conservancy and Civil Engineering, Xinjiang Agricultural University, Urumqi, Xinjiang 830052, China
College of Civil Engineering, Chongqing Three Gorges University, Chongqing, Sichuan 404100, China 
WANG Lin School of Water Conservancy and Civil Engineering, Xinjiang Agricultural University, Urumqi, Xinjiang 830052, China 
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Abstract:
      The seepage of plain reservoir raises the groundwater level of farmland behind the dam in arid area, which results the soil salinized. Consequently, production is reduced or even abandoned. It is an effective measure to control the farmland groundwater level to set drainage ditch behind the dam. The change of soil water and salt transport after changing groundwater depth is worth of studying. Therefore, drainage ditches was used to regulate the groundwater levels behind the dam in this study, and HYDRUS was used to simulate the soil water content and salinity at different soil depths and different groundwater levels. The reliability of the simulated values was verified by the measured data. The results showed that the groundwater level decreased from 1 to 3 m through drainage ditches and the difference of surface salinity was between 1.49~33.19 g·L-1. Therefore, the deeper the groundwater level in the drainage ditches, the less obvious the water\|salt migration,the less likely secondary salinization would occur. Otherwise, soil salinization would occur easily. When the groundwater level was the same, planting could be used to reduce water content and salt content, the maximum change of water content was 6.33%, the difference of salt content was only about 0.08~4.56 g·L-1 and the influence gradually decreased with the increase in soil depth. Therefore, setting drainage ditch is a best way to solve soil salinization behind dams to drain the seepage water from reservoirs in time.